It feels like Brendan Barber has worked for the union movement so long that he was probably sent to Australia with the rest of the Tolpuddle Martyrs and only recently came back. In fact he has worked for the TUC only since 1975, but his seven-year leadership as general secretary has recently experienced a change of gear.

Barber stresses that relations with David Cameron are functioning, and he does not feel, as under Thatcher, that the unions are about to be portrayed as the enemy within. Similarly relations with Vince Cable, the Lib Dem business secretary, are cordial, even if a kerfuffle ended with an invitation to speak to the TUC conference next week being withheld.

Instead, it is the governor of the Bank of England, Mervyn King, seen by some union leaders as the man that ushered in "the coalition of cutters" by so openly expressing his fears that the European economic crisis in the spring might engulf Britain, who is going to Manchester.

But Barber recognises that next week's conference is the most important for decades. Union membership – halved since the 70s – could slide further as public-sector jobs are shed, or the union movement could instead enjoy a renaissance as workers turn to the security they hope collective organisation can provide.

"We have to rise to this challenge," Barber says, promising to "mobilise opinion and popular support across the community as whole".

Barber's aim is to build a diverse community-based opposition to public spending cuts programme, and to make sure that the unions play a leading role in forming this broad popular front.

Doubtless the TUC next week will hear calls for general strikes and French-style street protests. A national demonstration is planned for March, but Barber stresses the strength of any resistance will depend on its grassroots support.

With the spending review not yet published and cuts not formally due until next April, Barber feels Britain is in a phoney war, and that this is the moment to marshall arguments. "At present it is a theoretical debate and the government can point to poll ratings showing public support, but once people begin to see the impact, and reality dawns, I think there will be a real reaction, " he says.

He warns: "We have got this whole cocktail of issues coming together: a pay freeze, significant job losses – the Office for Budget Responsibility said there was potential for 600,000 job losses in the public sector – privatisations, restructuring, a growing sense of job insecurity and the John Hutton review into the future of pensions. All of that adds up to a hell of an agenda of issues that could give rise to pretty difficult disputes."

Barber also argues that the coming dissent can claim a democratic legitimacy since the coalition cannot point to any manifesto mandate to try to eradicate the budget deficit in one parliament, a commitment that the TUC claims requires £99bn of spending cuts by April 2016.

"The Lib Dems of course fought the election saying this was not the time for immediate cuts. During the election campaign they supported one of our core arguments that now the priority is to secure a solid recovery. So has the coalition got a clear electoral mandate? Not with 30 something per cent of the votes [achieved by the Conservatives]. In the election, even the Tories talked only about efficiency savings, protecting frontline services and not increasing inequality."

But he concedes that public anger is well off boiling point. "I think we saw a glimmer of the reaction that is coming when Michael Gove cancelled the building schools for the future programme. I really do not buy this argument from ministers that these cuts are solely driven by necessity. I fear the Conservatives see this as a way of trying to recast the state in a dramatic way. They do not see this as a short-term adjustment to a crisis, but a long-term change in how the public sector operates in this country.

"They've set out to create this impression of imminent collapse and the financial markets turning against the UK in a dramatic way, but none of it has happened. There are respected economic commentators like Martin Wolf in the Financial Times that simply do not see the bond markets reacting in the way the coalition has predicted."

Without in any way endorsing Ed Balls as leader, Barber says the core arguments on the deficit that Balls advanced in his Bloomberg speech last month were "very powerful". Balls argued that the Labour election plan to halve the deficit in the next parliament went too fast.

The TUC general council statement, agreed in laborious talks on Thursday, does not set a specific timetable for eradicating the deficit, but says the government timetable is too fast. The Unite leadership, the biggest union inside the TUC, today called for the deficit reduction programme to be spread over two or three parliaments.

Barber will have to balance these competing interests and views inside the TUC while trying to keep a focus on the public. "We have to be a powerful campaigning organisation. We have to got to build a serious broad-based campaign."

But he insists the coalition must also consider how it deals with the unions. "Thatcher called us the enemy within. That was fundamentally anti-democratic. David Cameron has said that is not his intention with his government and I am hopeful he will meet us before the spending round."

There are noises from the Taypayers' Alliance, Policy Exchange and London's mayor, Boris Johnson, calling for action to recast union laws, or withdraw taxpayer support for union representatives.

So far, Barber says, he has detected no echoes of this agenda within government, but that climate could change. "We have to represent faithfully the views of our members. There are real fears about what may happen, and that may turn to real anger and there may be difficult disputes. But I don't think it makes sense to make unrealistic predictions for dramatic effect.

"One of the things the government does is try to portray us as representing a narrow interest against the rest of society. We have got to demonstrate that is absolutely false."

The TUC hitlist

According to research by the TUC, spending cuts will hit the poorest 10 times harder than the rich. These are the people in the front line:

•Single person household no children

People who live alone stand to lose £817 a year in public services, not including welfare payments. Proportion of household income lost is 4.9%.

•Couple with children

Families are more at risk of losing in the downturn. The costs are made up of social services, child support and for at least 11 years, education. The losses would equate to a 5% cut.

•Lone parent

The potential losses is only marginally more than for a couple at £1,883, largely made up from extra social care and housing services. As a proportion, the 11.2% loss is the most substantial of any group.

•Couple no children

Married or cohabiting couples with no children stand to lose £1,012 a year from transport costs. It equates to 3% of household income including the cost of the public services they use.

•Single pensioner

A single pensioner is at risk of losing £1,017 from services. The losses would amount to 8.7% of household income.

•Couple pensioner

An older couple require relatively less support compared with single pensioners and would lose less under the cuts - 4.8%. Older couples are much less likely to require social care support or housing payments. But they are more likely to use public transport.